Method and apparatus for adjusting excitation voltage of fingerprint detection chip

Abstract

The present disclosure provides a method and an apparatus for adjusting an excitation voltage of a fingerprint detection chip and a fingerprint detection chip. The method for adjusting an excitation voltage of a fingerprint detection chip includes: S1, transmitting an excitation signal to the metal ring by the signal transmitting unit, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; or enabling the metal ring grounded, and applying an excitation signal to the plurality of detection units in the second detection area by the signal transmitting unit, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; and S2, adjusting an excitation voltage of the first detection area according to the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring.

What is claimed is: 
     
       1. A method for adjusting an excitation voltage of a fingerprint detection chip, wherein the fingerprint detection chip has a signal transmitting unit, a first detection area, and a second detection area, each of the first detection area and the second detection area has a plurality of detection units, the first detection area is configured to detect a fingerprint capacitance, a metal ring is located over the fingerprint detection chip, and the metal ring at least partially covers the second detection area, the method comprising:
 S 1 , transmitting an excitation signal to the metal ring, by the signal transmitting unit, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; or 
 grounding the metal ring and applying the excitation signal to the plurality of detection units in the second detection area, by the signal transmitting unit, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; and 
 S 2 , adjusting the excitation voltage of the excitation signal of the first detection area according to the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring. 
 
     
     
       2. The method according to  claim 1 , wherein adjusting the excitation voltage of the excitation signal of the first detection area according to the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring comprises:
 when the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is greater than a first preset threshold and less than a second preset threshold, keeping the excitation voltage of the excitation signal of the first detection area to be constant; 
 when the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is less than or equal to the first preset threshold, increasing the excitation voltage of the excitation signal of the first detection area; and 
 when the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is greater than or equal to the second preset threshold, decreasing the excitation voltage of the excitation signal of the first detection area. 
 
     
     
       3. The method according to  claim 2 , wherein determining the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring comprises:
 calculating an average value of capacitance values of coupling capacitances formed between the plurality of detection units and the metal ring. 
 
     
     
       4. The method according to  claim 1 , wherein the first detection area is located at a central area of the fingerprint detection chip and the second detection area surrounds the first detection area. 
     
     
       5. The method according to  claim 1 , wherein transmitting an excitation signal to the metal ring, by the signal transmitting unit, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring comprises:
 transmitting the excitation signal to the metal ring, by the signal transmitting unit, when the signal transmitting unit is connected with the metal ring, so as to detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; 
 wherein enabling the metal ring grounded, and applying the excitation signal to the plurality of detection units in the second detection area by the signal transmitting unit, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring comprises: 
 grounding the metal ring when the signal transmitting unit is integrated in the first detection area or the second detection area and applying the excitation signal to the plurality of detection units in the second detection area by the signal transmitting unit, so as to detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring. 
 
     
     
       6. The method according to  claim 5 , wherein the fingerprint detection chip further comprises a plastic package area covering the signal transmitting unit, the first detection area and the second detection area. 
     
     
       7. The method according to  claim 6 , after increasing or decreasing the excitation voltage of the excitation signal of the first detection area, the method further comprising:
 increasing or decreasing the excitation voltage of the excitation signal of the second detection area correspondingly, and repeating S 1  and S 2  until the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is greater than the first preset threshold and less than the second preset threshold. 
 
     
     
       8. An apparatus for adjusting an excitation voltage of a fingerprint detection chip, comprising:
 a fingerprint detection chip, wherein the fingerprint detection chip comprises a first detection area, and a second detection area, each of the first detection area and the second detection area has a plurality of detection units, and the first detection area is configured to detect a fingerprint capacitance; 
 a metal ring located on the fingerprint detection chip, wherein the metal ring at least partially covers the second detection area; 
 a signal transmitting unit, configured to transmit an excitation signal to the metal ring, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; or configured to apply the excitation signal to the plurality of detection units in the second detection area when the metal ring is grounded, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; and 
 a control module, configured to adjust the excitation voltage of the excitation signal of the first detection area according to the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring. 
 
     
     
       9. The apparatus according to  claim 8 , wherein the control module is further configured to:
 when it is determined that the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is greater than a first preset threshold and less than a second preset threshold, keep the excitation voltage of the excitation signal of the first detection area to be constant; 
 when it is determined that the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is less than or equal to the first preset threshold, increase the excitation voltage of the excitation signal of the first detection area; and 
 when it is determined that the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is greater than or equal to the second preset threshold, decrease the excitation voltage of the excitation signal of the first detection area. 
 
     
     
       10. The apparatus according to  claim 8 , wherein the control module is further configured to:
 adjust the excitation voltage of the excitation signal of the first detection area according to an average value of capacitance values of coupling capacitances formed between the plurality of detection units and the metal ring. 
 
     
     
       11. The apparatus according to  claim 8 , wherein the first detection area is located at a central area of the fingerprint detection chip and the second detection area surrounds the first detection area. 
     
     
       12. The apparatus according to  claim 8 , wherein:
 the signal transmitting unit is configured to transmit the excitation signal to the metal ring when the signal transmitting unit is connected with the metal ring, so as to detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; 
 the signal transmitting unit is configured to apply the excitation signal to the plurality of detection units in the second detection area when the signal transmitting unit is integrated in the first detection area or the second detection area, and the metal ring is grounded, so as to detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring. 
 
     
     
       13. The apparatus according to  claim 8 , wherein the fingerprint detection chip further comprises a plastic package area covering the signal transmitting unit, the first detection area and the second detection area. 
     
     
       14. The apparatus according to  claim 13 , wherein after increasing or decreasing the excitation voltage of the excitation signal of the first detection area, the control module is further configured to increase or decrease the excitation voltage of the excitation signal of the second detection area correspondingly, to repeatedly detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring and adjust the excitation voltage of the excitation signal of the first detection area according to the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring until the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring is greater than the first preset threshold and less than the second preset threshold. 
     
     
       15. A fingerprint detection chip, comprising a signal transmitting unit, a first detection area and a second detection area, wherein:
 each of the first detection area and the second detection area has a plurality of detection units, 
 the first detection area is configured to detect a fingerprint capacitance; 
 the signal transmitting unit is configured to transmit an excitation signal to a metal ring, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; or configured to apply the excitation signal to the plurality of detection units in the second detection area when the metal ring is grounded, so as to detect a capacitance value of a coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; 
 the metal ring is located on the fingerprint detection chip and at least partially covers the second detection area. 
 
     
     
       16. The fingerprint detection chip according to  claim 15 , wherein
 the signal transmitting unit is configured to transmit the excitation signal to the metal ring when the signal transmitting unit is connected with the metal ring, so as to detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring; 
 the signal transmitting unit is configured to apply the excitation signal to the plurality of detection units in the second detection area when the signal transmitting unit is integrated in the first detection area or the second detection area, and the metal ring is grounded, so as to detect the capacitance value of the coupling capacitance formed between the plurality of detection units in the second detection area and the metal ring. 
 
     
     
       17. The fingerprint detection chip according to  claim 16 , further comprising a plastic package area covering the signal transmitting unit, the first detection area and the second detection area.